.container-fluid {
    background-color: darkred;
}

.col-md-2 {
    margin: 0;
    padding: 0;
    width: 200px;
    height: 600px;
    background-color: #f1f1f1;
    border-radius: 5px;
    border: 1px solid #555;
    text-align: center;
}

.left-menu {
    float: left;
}

.right-content {
    float: left;
}

#ul_head {
    background-color: grey;
}

.active {
    background-color: dimgrey;
    color: white;
}

#li_head1 a:hover:not(.active) {
    background-color: #555;
    color: white;
}

#li_head2 a:hover:not(.active) {
    background-color: #555;
    color: white;
}

#li_head3 a:hover:not(.active) {
    background-color: #555;
    color: white;
}